Breech mechanism for a recoilless gun



Feb. 13, 1968 F. w. DIETSCH 3,368,450

BREECH MECHANISM FOR A RECOILLESS GUN Filed Oct. 20, 1966' 2 Sheets-Sheet l o 28 39 40 F] l 42 INVENTOR.

FRANCIS W. DIETSCH Feb. 13, 19 F. W. DIETSCH 3,368,45G

BREECH MECHANISM FOR A RECOILLESS GUN Filed Oct. 20, 1966 2 Sheets-Sheet INVENTOR.

FRANCIS W. ETSCH United States Patent 3,368,45 BREECH MECHANISM FOR A RECOILLESS GUN Francis W. Dietsch, Levittown, Pa, assignor to the United States of America as represented by the Secretary of the Army Filed Oct. 20, 1966, Ser. No. 588,691 12 Claims. (Cl. 89-1.705)

This invention relates to a breech mechanism and, more particularly, to an improved mechanism for a recoilless rifle to make such a weapon lighter and safer than it has been heretofore. Another object is to render this gun automatically safe against being fired early in a swinging-open movement of a breech closure. A further object is to provide a number of locking mechanisms to guard against accidental or premature firing.

Heretofore the recoilless rifles of larger size have been provided with a safety mechanism which become effective late in a swinging-open movement of the breech closure with the result that a gun crew in a rapid fire contest were found to be able to insert a round before the swinging-open movement of the breech had been completed and before the safety mechanism became effective. This resulted in a dangerous practice of being able to close the breech and fire the round prematurely where the safety had not in fact become effective. According to this invention that practice has now been rendered impossible and a safer operation of the weapon has been provided. More specifically the early swing-open movement of the breech closure automatically renders the gun safe against being prematurely fired. In addition a plurality of locking and unlocking features, some of which are automatic and some manual, make rapid operation of this weapon safe while reducing the weight of the gun.

Referring to the drawings:

FIG. 1 is a longitudinal section through a preferred embodiment of the gun of this invention in a ready-to-fire position.

FIG. 2 illustrates a partial exterior view of the safety lever arrangement of the FIG. 1 construction with parts broken away in section.

FIG. 3 is an enlarged view partially in section of a rotary camming arrangement for the hammer of FIG. 1.

FIG. 4 is a sectional view along line 44 of FIG. 1.

In FIG. 1 a bar type breech closure is of the general sort exemplified in the prior patent to Shapiro et al. 2,884,837 dated May 5, 1959, for Lightweight Recoilless Gun. This closure is airfoil shaped to have its opposite sides forming portions of opposite venturi passageways (not shown) that exhaust the gas for recoil counter-action. Short interrupted thread portions 12 or buttress type projections longitudinally spaced by interconnecting recesses engage correspondingly shaped interrupted thread portions 13 on the gun nozzle 11. A hinge bar 14 supports closure 10 and is pivoted on the hinge pin 15 to enable the closure to open for loading the gun. Substantially axially aligned with the longitudinal axis of the gun barrel is a forwardly projecting spindle 16 integral with the bar 14 to provide a hub on which the breech closure 10 may be rotated into and out of a fully closed and locked position as is known in the art. At the other end of bar 14 is another forward projection 17 which includes a cylindrical terminal or journal 18 inolosing hinge pin 15. Longitudinally slidable within the spindle 16 is a hammer 19 driven forward by the spring 20 for effecting percussion firing of a primer in a round (not shown) by means of a firing pin 22 carried by the hammer 19. Key 19a carried by the hammer extends laterally into spindle slot 16A to preclude rotation of hammer 19 relative to spindle 16. Spring 20 engages the hammer 19 for driving it forward when freed to do so. At its opposite or rear end 3,368,450 Patented Feb. 13, 1968 the spring engages a cap 21 suitably threaded onto a rear projection of the bar 14.

A sear 23 when raised releases hammer 19 for firing a round. This sear is slidable within bar 14 in response to sliding movement of a sear rod 24 actuated from a catch 25 pulled by a flexible tension member 26 for firing the gun. Upon movement of scar rod 24 forward or to the right in FIG. 1, the inclined projection causes sear pin 28 to ride up the top surface of projection 27 at the rear end of sear rod 24, lifting sear 23 out of the notch or groove 49 in which it has been seated while holding the hammer against the forward pressure exerted thereon by its spring 20. On movement of sear rod 24 to the left in FIG. 1, projection 27 causes sear pin 2-9 to be moved downward along the lower surface of the projection 27, carnming sear 23 downward to engage notch 59 and hold hammer 19 against the pressure of its spring 20. Pin 30 projects through firing pin 22 to limit its travel and prevent a back fire flame carbonizing the exterior surface of the firing pin making it difficult to move.

A longer pin 31 projects through closure 10 into circumferential arcuate slots in the spindle 16 which are of a length to accommodate angular movement of closure 10 to and from its locked position and also to retain the spindle 16 fixed with closure 10. One or more inclined cam surfaces or rotary cam slots 32, 32A (FIGS. 1 and 3) in hammer 19 effect a rearward translation of the hammer 19 as closure 10 is rotated to disengage threads 12 and 13, the hammer being prevented from turning by the aforementioned =key arrangement. A locking pin 33 extends through closure 10 and into the spindle 16 for locking the closure 10 in its fully closed position. Upon counterclockwise rotation of pivotable handle (FIG. 1) about its pivot pin 35, and projection 36 which is integral with knob 34 engages pin 33, moving it radially outward compressing spring 37. This enables closure 10 to be rotated by the handle knob 34 about the spindle 16 and bar 14 until the closure threads 12 are clear of the locking recesses and projections or interrupted threads 13. The closure 10 with bar 14 may then be swung open and closed about hinge 15.

To fire a round loaded in the gun, the cable 26 is pulled to the right directly or by any appropriate trigger mechanism or equivalent thereof. Pulling cable 26 (FIG. 1) moves the catch 25 and sear rod 24 engaged therewith to the right until catch 25 abuts an appropriate recess wall 42 on shaft 40, raising sear pin 28 and withdrawing sear 23 from hammer notch 49. The released hammer 19 is then moved to the right under spring pressure and fires the round. The round may be of the caseless type, or provided with a consumable case or an appropriately apertured metal case that needs to be withdrawn. After breech closure 10 has been rotated from a fully closed position to a position in which it is free of the interrupted locking threads, it is ready to be swung open about hinge pin 15.

Upon clockwise rotation of hinge bar 14, integral projection 17, and sear rod 24 in projection 17 during a swing-open movement of the breech closure about hinge pin 15, cam 38 on the journal 18 engages safety actuator pin 39 moving it to the right in FIG. 1 to engage a suitable recess in shaft 40 on which the safety lever 41 (FIG. 2) is carried. As the breech closure 10 is swung open sear rod 24 (upon rotation about hinge 15) becomes disengaged from the catch 25 While the catch is still in its fired or firing position and shaft 40 is rotated clockwise by cam 38 such that safety lever 41 is moved to the safe position designated by theletter S in FIG. 2. In such movement, the catch 25 is moved to the left to its FIG. 1 cocked position by abutment wall 42 without the sear rod 24 and sear 23 having been returned to their FIG. 1 readyto-fire position. During the swinging open and close motion of the closure 10, spring 20 is held compressed by pin 31.

Late in the swinging-closed motion, of closure the sear rod 24 still in its rightmost or fired position is moved leftward by its inclined surface 44 striking the corner 43A catch 25 which has been previously returned to its leftmost or cocked position. As the rod 24 reaches its leftmost position, sear 23 is moved by its pin 29 into notch 49 to lock the hammer 19 in its cocked position and rod 24 is re-engaged with catch 25. Upon completion of the swinging-closed movement of the breech closure parts are in their ready-to-fire position except as to the safety lever which is still in its safe or S position, and the lever 41 and its shaft 40 must be moved manually to the FIG. 1 or F position with pin 39 again contacting cam 38 on journal 18. The closure 10 is then rotated by knob 34 to its fully closed position where interrupted thread portions 12 and 13 are interengaged. During the last 3 to 6 degrees of such rotation of closure 10 to its fully closed and locked position, the spring detent 4-5 (FIGS. 1 and 4) is moved slightly to the left (FIG. 1) or downwardly (FIG. 4) by an adjacent camming surface 10C to compress spring 46 and unlatch detent projection 48 as detent 45 is moved further leftward (FIG. 1) out of the recess 47 in sear 23, leaving sear 23 free to be moved upward upon actuation of cable 26 for firing the gun. Prior to these last few degrees of rotation of closure 10, the gun could not be fired since detent projection 48 was engaged in sear recess 47, the hammer remaining cocked because its notch 49 retains the tip of sear 23.

The forward central opening 50, defined by the inwardly extending circumferential flange 51 of hammer 19, slidingly receives the rearmost shaft portion 52 of the firing pin assembly. The forward shaft portion 53 is threadedly secured to shaft portion 52 and its rear face or flange 54 is longitudinally spaced sufficiently forward of an appropriately secured rear enlargement or head 55 to provide a lost motion connection with hammer 19 through alternative engagement with its circumferential flange 51. The closure aperture 56 has a forwardly facing flange 57 that serves as a seat for laterally extending flange 58 on shaft portion 53 adjacent the firing pin 22. Preferably, an aligned transverse slot means 59, 60 are provided in shaft portions 52, 53 to receive with substantial clearance the transverse stop or restraining pin 30 which is suitably secured to the closure 10.

Various modifications, changes and alterations may be resorted to without departing from the scope of the invention as defined by the appended claims.

I claim:

1. A breech closure mechanism for a recoilless gun comprising:

a breech bar having a longitudinally extending spindle and rotatably mounted about a fixed transverse post, said spindle having transversely apertured wall means,

a spring biased hammer longitudinally slidable in said spindle for actuating a longitudinally movable firing pin and having arcuate slot means and a peripheral notch therein,

a closure rotatably mounted upon said spindle and having a forward aperture slidably receiving said firing pin and aligned with said hammer,

a camming member secured to said closure and extending through said apertured Wall means and into said arcuate slot means for retracting said hammer upon rotation of said closure,

a scar member slidably mounted in said bar and having one end portion engageable in said hammer notch when said hammer is retracted, and

means for moving said sear one end in and out of engagement with said hammer notch.

2. The structure in accordance with claim 1 wherein said sear is provided with a slot, said bar includes a spring detent for engaging said sear slot when sear one end is engaged in said hammer notch and means on said closure for unseating said spring detent when said camming member is returned to an ineffective position.

3. The structure defined in claim 1 in which said hammer has a forward central opening,

an inwardly extending circumferential flange defining said opening,

a firing pin assembly slidably mounted in said opening and having longitudinally spaced flanges for alternative engagement by said circumferential flange.

4. The structure of claim 3 wherein said hammer and firing pin assembly flanges define a lost motion connection.

5. The structure of claim 3 in which a forward portion of said firing pin assembly has a transverse aperture therein, and a restraining pin extending through said transverse aperture and secured to a forward portion of said closure.

6. The structure set forth in claim 3 wherein said closure aperture includes a forwardly facing flange, and said firing pin assembly has a laterally extending flange adjacent the firing pin for engaging said closure forwardly facing flange.

7. In a recoilless gun having a bar type flattened breech closure constituting portions of a pair of venturi passageways on its opposite sides,

means for locking said breech closure in its fully closed position,

means for rotatably engaging and disengaging said locking means,

means whereby said closure may be swung to a fully opened position, and swung closed, the combination therewith of the improvement enabling said gun to be operated with greater safety, said improvement including means for firing said gun and including a pull cord,

a locking lever,

means responsive to an early swinging-open position of said breech closure for moving said locking lever to a safe position,

a sear, a scar rod for moving said sear, a catch for moving said sear rod, means also responsive to an early swinging-open position of said breech closure for separating said sear rod and catch to preclude the gun being fired by said pull cord during a swing-open movement of said closure,

a hammer, a spring for moving said hammer forward to fire said gun, said sear engaging said hammer to hold the same in position with said spring stressed for firing said gun,

a spring detent for engagement with said sear to hold the same against being release, said spring detent engaging said sear in response to a radial inward movement of said sear during a late swinging closed movement of said breech closure, said means for locking said breech closure in its fully closed position being manually operable to hold said closure in such position until said locking means is manually unlocked, and

said spring detent being movable to disengage said sear during the last about 3 to 6 of rotation of said closure in moving to its fully closed position.

8. A gun according to claim 7 in which said locking lever is manually shiftable from a safe to a firing position, said closure is rotatably mounted upon a fixed spindle,

a pin secured to said closure and extending through said spindle and hammer, and

a cam surface on said hammer and cooperating with said pin to effect rearward movement of said hammer as said closure is rotated preparatory to being swung open.

9. A gun according to claim 8 in which said catch is moved rearward during said early swinging open movement of said closure and said catch is reengaged by said sear rod during a late swinging-closed movement of said closure, and

a cam surface on said sear rod engages an end portion of said catch to slide said sear rod rearward for effecting radial inward movement of said sear and locking of said sear in position holding said hammer with its Spring compressed.

10. In a recoilless gun having a bar breech closure constituting side walls of opposite venturi passageways through which products of combustion from a propellant may issue, a hinge about which said bar breech closure may be swung for loading a round of ammunition for said gun, said hinge including an upstanding pin and a bar pivotally secured about said pin, means for pivotally mounting said bar breech closure to said pivotally secured bar in axial alignment with a chamber of said gun, a handle secured to said bar breech closure by means of which may be angularly displaced with respect to said pivotally secured bar and such bar swung about said pin, and means for locking said closure in poistion for firing a round of ammunition,

the combination therewith .of the improvement for enhancing safety for percussion firing a round Without danger of premature loading and ignition, said improvement including a sear slidingly mounted in said bar,

a projection from said bar to said pin,

a sear rod slidable Within said projection,

means for shifting said sear in response to shifting said sear rod,

a flexible pull connection for firing a loaded round and effecting forward movement of said sear rod, and

a safety device between said sear rod and flexible pull connection and having a safe position and a firing position, said safety device being manually movable from a safe position to a firing position but movable from a firing to a safe position in response to an early swinging-open movement of said bar and bar breech, said safety device being locked against movement to a safe position from a firing position when said bar breech is closed, a connection between said sear rod and sear for effecting translation of the sear in resonse to a shifting of said sear rod from either of its extreme positions to the other extreme position.

11. Apparatus according to claim 10 in which said safety device includes a lever, a shaft parallel to said hinge pin, a cam surrounding said hinge pin, a pin received within a notch in said cam and in said shaft, said shaft having an angularly spaced notch, a slidable member for engaging said sear rod and said angularly spaced notch in said shaft and returning said sear rod and sear to a safe position on initiation of a swinging-open movement of said bar after the gun has been fired.

12. Apparatus according to claim 10 in which said sear is provided with a spring pressed detent holding said sear in a safe position until the last 3 to 6 of closing rotation of said bar breech.

No references cited.

SAMUEL W. ENGLE, Primary Examiner. 

1. A BREECH CLOSURE MECHANISM FOR A RECOILLESS GUN COMPRISING: A BREECH BAR HAVING A LONGITUDINALLY EXTENDING SPINDLE AND ROTATABLY MOUNTED ABOUT A FIXED TRANSVERSE POST, AND SPINDLE HAVING TRANSVERSELY APERTURED WALL MEANS, A SPRING BIASED HAMMER LONGITUDINALLY SLIDABLE IN SAID SPINDLE FOR ACTUATING A LONGITUDINALLY MOVABLE FIRING PIN AND HAVING ARCUATE SLOT MEANS AND A PERIPHERAL NOTCH THEREIN, A CLOSURE ROTATABLY MOUNTED UPON SAID SPINDLE AND HAVING A FORWARD APERTURE SLIDABLY RECEIVING SAID FIRING PIN AND ALIGNED WITH SAID HAMMER, A CAMMING MEMBER SECURED TO SAID CLOSURE AND EXTENDING THROUGH SAID APERTURED WALL MEANS AND INTO SAID ARCUATE SLOT MEANS FOR RETRACTING SAID HAMMER UPON ROTATION OF SAID CLOSURE, A SEAR MEMBER SLIDABLY MOUNTED IN SAID BAR AND HAVING ONE END PORTION ENGAGEABLE IN SAID HAMMER NOTCH WHEN SAID HAMMER IS RETRACTED, AND MEANS FOR MOVING SAID SEAR ONE END IN AND OUT OF ENGAGEMENT WITH SAID HAMMER NOTCH. 